How much food for 8 month old

My son is on a regular feeding schedule with his formula. He will go 3 1/2 to 4 hours but I’m confused with giving him food. At first I thought I wasn’t giving enough but now I feel I may be giving too much. He’s 8 months today. Last week I was doing his bottles and then at lunch giving 2 oz and for dinner time/before bed giving 4oz. This week I started giving 2oz for breakfast, 2oz for lunch and 4oz for dinner. I noticed his belly seemed to be hurting lastnight and his sleep was awful. I think maybe from over feeding. How much are y’all giving your babies at this age?